1. Field of the Invention
The present invention relates to non-contact power transmission devices for performing wireless electric power transmission.
2. Description of the Related Art
Recently, non-contact power supply devices which wirelessly supply electric power to apparatuses without power cables or the like have come to be in practical use. The principles upon which wireless electric power transmission is realized are generally categorized into three types: electromagnetic induction type; radio reception type; and resonance type.
Electromagnetic induction non-contact power transmission employs the phenomenon in which application of an electric current to one of adjacent coils induces an electromotive force in the other coil with magnetic flux as the medium. This technique has gradually become widespread in non-contact charging of mobile terminals.
In radio reception non-contact power transmission, radio wave energy is transmitted and received using antennas, and AC waveforms of radio waves are converted into DC waveforms using rectifier circuits, without using amplifiers or the like.
Resonance non-contact power transmission utilizes either electric resonance or magnetic resonance. For example, United States Patent Application Publication No. 2007/0222542 discloses a technique of transferring electric power using magnetically coupled resonators.